Then do it by death proportionality but don just wholesale ban a whole group
You've got that right. For the sake of argument, let's assume that a single Canadian soldier died in that battle. That man would deserve to be respected, and remembered. So in that case, at least one Canadian should be allowed to attend the ceremony.
The British have taken the same approach at their Thiepval memorial. It’s the only practical way countries are finding to do it.